<!--
 * @Description: 
 * @version: 
 * @Author: Eve
 * @Date: 2019-10-08 13:05:02
 * @LastEditors: Eve
 * @LastEditTime: 2019-10-08 13:12:00
 -->
<!DOCTYPE html>
<html lang="zh">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .shape {
      border-width: 30px;
      border-style: solid;
      border-left-color: transparent;
      border-right-color: transparent;
      border-bottom-color: red;
      border-top-color: transparent;
      width: 0;
      height: 0;
      border-radius: 50%;
      /* 可以画扇形 */
    }
  </style>
</head>

<body>
  <div class="shape"></div>
</body>

</html>